Data representation

Selecting the type of representation (or graph) depends on the type of data.

• The most common forms of representation for categorical (or categorised) data are the bar chart or pie graph.
• For numerical data, the number of data values will affect the selection.
• The most appropriate form of representation for smaller numerical data sets is likely to be the stacked dot plot or the stem-and-leaf plot. These are adaptable for comparing two data sets.
• Histograms are a useful graphical form for large numerical data sets. Box plots, which show a summary of the data in five values, are also useful for large data sets.

Other representations should also be considered. A scatter plot is appropriate for showing an association between two variables measured on the same cases.